Heat-developable diazotype material

ABSTRACT

Diazo-type material readily developable by heat, having good keeping quality, and producible economically by aqueous coating techniques, comprises a light-sensitive layer containing, with a diazo compound, an acid-reacting stabilizer and a water-soluble hydrophilic organic binder, a substantially water insoluble acylacetamide as azo-coupling component and a substantially water insoluble developing agent, each dispersed as particles of .01-10 microns average size, the developing agent when heated above 100* C. creating a medium wherein coupling occurs, the acylacetamide melting above 50* C. and having solubility of less than 1 X 10 3 mol/liter in water at 20* C. The acylacetamide is yellow-coupling. Its use with a blue-coupling compound provides material that develops a black image, as by the use of dispersed particles of a N,N&#39;&#39;-bis(acylacet)-alkyl-enediamine with 2,3dihydroxynaphthalene-6-sulfonic acid or a salt thereof.

United States Patent [72] Inventors Leonardus Jacobus Antonius Giesen; Hubertus Wilhelmus Henricus Maria Roncken, both of Venlo, Netherlands [21] Appl. No. 685,287

[22] Filed Nov. 24, 1967 [45] Patented Oct. 26, 1971 [73] Assignee Van Der Grinten N.V. Venlo, Netherlands [32] Priority Dec. 2, 1966 [3 3] Netherlands [54] HEAT-DEVELOPABLE DIAZOTYPE MATERIAL 11 Claims, No Drawings [52] U.S. Cl 96/75, 96/49, 96/91 R [51] Int. Cl G03c 1/58 [50] Field of Search. 96/91 R, g 49; 1/75 [56] References Cited UNITED STATES PATENTS 1,989,065 1/1935 Schmidt etal. 7 96/91 X 2,537,106 l/1951 Von Glahn et al.. 260/152X 2,727,820 12/1955 Botkin et al. 96/91 X 3,284,201 11/1966 Meysetal 96/91X 3,416,924 12/1968 Tummers... 96/91X 3,420,665 1/1969 Bialczak .96 91x ABSTRACT: Diazo-type material readily developable by heat, having good keeping quality, and producible economically by aqueous coating techniques, comprises a light-sensitive layer containing, with a diazo compound, an acid-reacting stabilizer and a water-soluble hydrophilic organic binder, a substantially water insoluble acylacetamide as azo-coupling component and a substantially water insoluble developing agent, each dispersed as particles of .01-10 microns average size, the developing agent when heated above 100C. creating a medium wherein coupling occurs, the acylacetamide melting above 50 C. and having solubility of less than 1X10 mol/liter in water at 20 C. The acylacetamide is yellow-coupling. Its use with a blue-coupling compound provides material that develops a black image, as by the use of dispersed particles of a N,N'-bis(acylacet)-alkyl-enediamine with 2,3-dihydroxynaphthalene-6-sulfonic acid or a salt thereof.

HEAT-DEVELOPABLE DIAZOTYPE MATERIAL This invention relates to new and improved heat-developable diazo-type material.

In a known type of heat-developable diazo-type material, a light-sensitive layer formed on a support contains a diazo compound, an azo-coupling component, a stabilizing acid or similar acid-reacting component (which counteracts decomposition of the diazo compound as well as premature coupling of diazo compound and azo-coupling component), and a substance which promotes the coupling reaction upon heating of the material-called the developing agent, all of which are present on the support in such a condition that the coupling reaction proceeds readily only if the material is heated to 100 l 50 C.

Many proposals have already been made to obtain heatdevelopable diazo-type materials having good keeping quality. For economic reasons, the most interesting materials are those in which all the said components are present in one hydrophilic layer, i.e., a layer which has been formed in one or more steps with the aid of one or more aqueous coating compositions. However, it is with just such one layer materials difficult to combine good keeping quality with ready and complete development. By good keeping quality is to be understood a keeping quality corresponding with the shelf life of a comparable two-component diazo-type material which is developed in ammonia vapor. Complete development means that more than 80 percent, preferably 90 percent or more, of the diazo compound is converted into azo-dyestufi'.

Thus far, it has not been possible to produce with the aid of water-soluble developing agents one-layer materials having good keeping quality and showing at the same time ready and complete development upon heating. Better results are obtained with water-insoluble developing agents. Heat-developable one-layer materials are known the light sensitive layer of which contains, in the form of dispersed finely divided particles, a developing agent which dissolves less than 2 g./liter in water of 20 C. and upon heating creates a medium in which coupling of the diazo compound and the azo-coupling component is possible.

Dutch Pat. application 6,402,452 corresponding to U.S. Pat. No. 3,416,924, issued Dec. 17, 1968, describes heatdevelopable diazo-type material making use of a dispersed developing agent which is a water-insoluble salt obtained by the reaction of an aliphatic amine having the formula wherein R represents an aliphatic hydrocarbon radical having at least eight carbon atoms, and R and R each stands for a hydrogen atom or an aliphatic hydrocarbon radical, R R and R together carrying at least 16 carbon atoms, with a polybasic acid the first dissociation constant of which lies between 7X l and lXlO. The salt contains at least two cations derived from an amine conforming to the above definitron.

Japanese Pat. application 7832/6l mentions wax-enveloped barium hydroxide particles as a developing agent for heatdevelopable diazo-type material.

lrish Pat. application 1265/63 proposes the use, as a dispersed developing agent in heat-developable diazo-type material, of water-insoluble particles obtained by adding a base or a basic-reacting salt to a melt or a solution of a resin or a wax (which resin or wax may carry carboxyl groups) and isolating the product thus obtained in the form of fine particles.

Dutch Pat. application 6,600,540 describes the use of complex compounds of a substance having an amine function with a substance having an acid function as water-insoluble developing agents in heat-developable diazo-type material. The substance having the amine function may be a resis (e.g. an aminoplast), a copolymer of styrene with divinylbenzene into which aminogroups have been introduced, or an aliphatic or aromatic amine. The substance having the acid function may be a polymer carrying carboxyl groups, a fatty acid, a synthetic wax carrying carboxyl groups, an aliphatic or aromatic dicarboxylic acid, or a resin of the phenolformaldehyde type, capable of cation-exchange.

Belgian Pat. application 29,782, corresponding to U.S. Pat No. 3,493,374, issued Feb. 3, 1970, describes the use, as water-insoluble dispersed developing agents for heatdevelopable diazo-type material, of compounds formed by the reaction of an alkane dicarboxylic acid having at least three carbon atoms in a straight chain between the carboxyl groups with an amino-1,3,5-triazine having the formula in which X represents hydrogen, alkyl, branched alkyl, aralkyl, or a group having the formula Y stands for hydrogen or a group having the formula R and R represent identical or different atoms or groups of atoms selected from hydrogen atoms, alkyl, branched alkyl, unsaturated alkyl, cycloalkyl, and aralkyl groups, or stand for the atoms required for the completion of a heterocyclic ring, and R and R represent identical or different atoms or groups of atoms selected from hydrogen atoms, alkyl, branched alkyl, unsaturated alkyl, cycloalkyl, and aralkyl groups or stand for the atoms required for the completion of a heterocyclic ring, or R stands for a hydrogen atom and R for an aryl group.

In heat-developable diazo-type materials containing a water-insoluble dispersed developing agent preferably a hydrophilic organic binder is used in addition to the developing agent, the diazo compound, the azo-coupling component, and an acid-reacting compound. It may also be advantageous to incorporate in such materials other auxiliary agents known to be useful in one and two-component diazo-type materials.

The production of heat-developable diazo-type material with the aid of a water-insoluble, but readily dispersible developing agent is fairly simple. With a right selection of developing agent and other chemicals the quality of the material equals that of comparable conventional two-component diazo-type material for development with ammonia vapor. However, the stabilization of the material has to be effected with care, for the quantity of acid should be adapted rather precisely to the quantity of developing agent to be applied in the material. This means that combinations of diazo compounds and azo-coupling components which are hard to stabilize cannot be employed.

Materials having good keeping quality can be obtained using the combinations of diazo compounds and azo-coupling components commonly employed in the conventional bluedeveloping two-component diazo-type materials, but the application of very active azo-coupling components, such as acetoacetanilide and phloroglucinol, involves difficulties with regard to the stabilization, unless these azo-coupling components are present with a diazo compound which has extremely low coupling activity. Such diazo compounds having extremely low coupling activity as a rule do not meet the modern requirements of light sensitivity.

In the two-component diazo-type process black-developing diazo-type materials areproduced by incorporating in the material a yellow-coupling azo-component (a so-called shading component) in addition to a blue-coupling azo-component. The shading component, as a rule, possesses a considerably higher coupling activity than the blue-coupling azocomponent. The outstanding blue-coupling azo-component is 2,3-dihydroxynaphthalene--sulfonic acid which may or may not be in the form of a water-soluble salt). But also 2,3- dihydroxynaphthalene, 2,7-dihydroxynaphthalene-3,6-disulfonic acid, and the B-ethanolamide of Z-hydroxynaphthalene- 3-carboxylic acid are blue'coupling azo-components of practical importance. A shading component frequently used in the two-component diazo-type process is acetoacetanilide.

Heat-developable one-layer diazo-type material which, upon development, yields black azo-dyestuff images has usually been composed in the same way as black-developing conventional two-component diazo-type material. Up to the present, however, such a heat-developable diazo-type material which, as to light-sensitivity, keeping quality, and cost, can bear comparison with conventional black-developing twocomponent diazo-type material is neither known from the literature nor commercially available.

As has been stated above, because of their high coupling activity shading components such as acetoacetanilide cannot be used in the light-sensitive layer of heat-developable diazo-type material without involving difficulties.

It has also been proposed to apply dispersed particles of an azo-coupling component in the light-sensitive layer of heatdevelopable diazo-type material.

French Pat. Specification 1,249,913 described heatdevelopable diazo-type material which contains an acid having a dissociation constant greater than 1X10 as the stabilizer, with urea, thiourea or an alkyl derivative thereof as the developing agent. The azo-coupling component may be, for instance, 2,3-dihydroxynaphthalene, 2,3-dihydroxynaphthalene-6-sulfonic acid, l-hydroxynaphthalene-4-sulfonic acid, phlorogucinol, acetoacetanilide, or l-(4'-ethoxycarbonylphenyl)-3-dodecylpyrazolone(5). The azo-coupling components 2,3-dihydroxynaphthalene and l-(4'-ethoxycarbonyl-phenyl)-3-dodecylpyrazolone(5) are not readily water soluble. They are therefore dissolved in an organic solvent and this solution is suspended in an aqueous pretreatment or sensitizing liquid. Material prepared according to French Pat. Specification 1,249,9l3 with application of the said nonreadily soluble azo-coupling components has insufficient keeping quality.

The object of the present invention is to provide a diazotype material which readily develops upon heating and has good keeping quality, and whose light-sensitive layer contains an acylacetamide of high coupling activity as a yellowcoupling azo-component.

More particularly, the invention makes it possible to produce a diazo-type material developing black upon heating, and having good keeping quality, which can also compete with black-developing conventional two-component diazo-type material as to light-sensitivity and cost of manufacture. The heat-developable diazo-type material of this invention comprises a support carrying thereon a light-sensitive layer which contains'a diazo compound, an azo-coupling component, an acid-reacting compound, a water-soluble hydrophilic organic binder, and a developing agent; the developing agent being a compound (advantageously, a reaction product of an organic amine and an organic dicarboxylic acid, such as products of this nature disclosed in the aforementioned Dutch Pat. Application 6,402,452 or Belgian Pat. Application 29,782) which dissolves less than 2 g./liter in water of 20C., is present in the layer in the form of dispersed finely divided particles, creates upon heating of the diazo-type material above 100 C. a medium in which coupling of the diazo compound and the azocoupling component can occur, and has an average particle size between 0.1 and microns; and the azo-coupling component being a compound which a. has the general formula R CH,COR,, in which R is an acyl group and R is an amido residue derived from a primary amine having a molecular weight of at least 150,

b. melts above 50 C.,

c. dissolves less than 1X10 mol/liter in water of 20C., and

d. is present in the layer in the form of dispersed particles having an average size between 0.1 and 10 microns. 4

Because both the azo-coupling component and the developing agent are practically water-insoluble but at the same time readily dispersible, the present invention furnishes the possibility of producing in a simple and consequently inexpensive way heat-developable diazo-type material having good keeping quality. This diazo-type material, if it contains only the acylacetamide as its azo-coupling component, yields upon imagewise exposure and heating to IOU-150 C. copies having a yellow azo-dyestuff image which has high absorption for the U.V.-radiation (3,6004,400 AU) commonly applied in the diazo-type process. If, however, a quantity of a further azocoupling component is used in the material, the copies may shown azo-dyestuff images of a different shade. Thus, a diazotype material according to the invention which develops black upon heating can be obtained by incorporating an appropriate quantity of a blue-coupling azo-component in the material.

The acyl group of the acylacetamides which are suitable for application in the diazo-type material according to the invention may be widely varied. Practical acyl groups to be mentioned are, for instance: acetyl, propionyl, butyryl, pivaloyl, chloroacetyl, phenacetyl, stearoyl, benzoyl, naphthoyl, furoyl, 2,5-diethoxybenzoyl, Z-methoxybenzoyl, benzofuroyl. and thiophenylcarbonyl.

The amido residue is derived from a primary amine having a molecular weight of at least I50. (If the amine is polyvalent and carries more than one acylaceto group, for the calculation of the molecular'weight of the amine from which the amido residue has been derived the further acylacetamino groups are looked upon as substituents to the hydrocarbon radical combined with the first amino group). Suitable amines are, for instance: decylamine, dodecylamine, hexadecylamine, octadecylamine, 9-octadecenylamine, 9,l2-octadecadienylmaine, 6-(phenyl)hexylamine, aniline derivatives carrying an acylamino group and possibly one or more alkyl, alkoxy, or halogen substituents to the phenyl nucleus, 4-dodecylaniline, 4-phenyland 4-tolylthio-anilines the phenyl nuclea of which may carry further substituents, such as alkoxy, alkyl or acylamino, heterocyclic amines such as 2-amino-6ethoxybenzothiazole. Polyvalent amines, such as hexamethylene diamine, octamethylene diamine, decamethylene diamine, dodecamethylene diamine, p-menthane-l,8-diamine, and 3,3 -diamino-dipropylamine, are also eminently suitable for the preparation of water-insoluble acylacetamides which can be applied in the diazo-type material according to the invention, provided that in all the amino groups an acylaceto radical is introduced or that in one of the groups an acylaceto radical is present and the other amino groups are substituted in such a way that they show no longer a marked basic character, for instance because they carry an electronegative substituent such as an acyl group or a phenyl group. Suitable acylacetamides can be obtained from the amines mentioned above by reacting them with an alkyl ester of an acylacetic acid or with diketene.

Because of their good accessibility, particularly attractive compounds are the acetoacetamides, which can be obtained very easily by reacting a suitable primary amine with diketene.

The acylacetamides have to melt above 50 C., preferably above C., because otherwise the particlelike division in which they have to be present in the light-sensitive layer is lost too easily during the drying process(es) which is (are) required in making the diazo-type material.

Of course, not all the azo-coupling components satisfying the above-mentioned requirements are equally useful. Generally, the diazo-type material according to the invention has better keeping quality according as the acylacetamide has lower water-solubility and lower coupling activity.

The water-solubility of acylacetamides which dissolve more than 1X10 moi/liter in water and which show a selective absorption spectrum can be determined as follows:

A solution of 1X10 mol/liter of the acylacetamide in ethanol (96 percent) is prepared.

If the acylacetamide does not dissolve completely or does not give a clear solution, a new solution is prepared which contains lXiO mol of the acylacetamide per liter of ethanol. All the acylacetamides, so far known to the applicants, dissolve more than 1X10" moi/litre in ethanol. If, on dilution of 1 ml. of this solution to 100 ml with distilled water, the acylacetamide precipitates, it may be assumed to dissolve less than lXlO mol/liter in water. Successively, l 2, and 3 ml. of the alcoholic solution of the acylacetamide are diluted to I ml. with distilled water. The E-max (and the A max) of these dilute solutions in the range between 2,000 and 3,500 AU are determined in a spectophotometer. It appears from the E- values thus obtained whether Beer-Lamberts law is fulfilled. This always applies, unless precipitation occurs in one of the dilute solutions. Then I g. of the acylacetamide to be tested is mixed with 10 ml. of distilled water and the mixture'is intensively shaken for 24 hours at a temperature of 20 C. The nondissolved substance is filtered off with the aid of a porcelain filter crucible having an average pore size of 6 microns. ml. of the filtrate is mixed with 2 ml. of ethanol (96 percent) and the mixture is diluted to 50 ml. with distilled water. The extinction at the A max of the solution thus obtained is measured. If the extinction is found to be too high, i.e. if it lies outside the range where the spectrophotometer gives reliable values, the mixture is further diluted with distilled water until the concentration falls within the desired range. From the E- max value thus obtained the molarity of the undiluted solution is calculated with the formula.

d.a.m. Ev-L...

in which d represents the optical density found of the dilute saturated solution of the azo-coupling component, a is the dilution factor, M is the molecular weight of the azo-coupling component, E is the molar extinction, and l is the thickness of the layer of the liquid measured (i.e. the length of the path of the measuring light trough the cell).

If the acylacetamide shows no selective spectrum, its watersolubility can be determined as follows, provided its solubility in ethanol (96 percent) amounts to at least 1X10 mol/liter. Three solutions are prepared:

A. A solution containing lXlO mol/liter of the acylacetamide in ethanol (96 percent) B. A solution containing lXlO' moi/liter of 4-ethoxybenzene diazonium chloride, zinc chloride double salt, in distilled water C. A saturated solution of sodium acetate in distilled water D. An acid liquid obtained by mixing 50 ml. of sulfuric acid l3N with 333 ml. of distilled water and bringing the volume ofthe mixture up to 2,000 ml. with dioxane.

5 ml. of solution A, 20 ml. of solution B, and 2 ml. of solution C are combined, and the reaction mixture is kept in the dark for 20 hours at a temperature of 20 C. In this period of time all the azo-coupling component has coupled. Then the acid liquid D is added to obtain a volume of 50 ml., and the A max and the optical density (O.D.l) at the A max are determined in a spectrophotometer in order to obtain the reference value. Then 2 g. of the acylacetamide are mixed with 20 ml. of water and the mixture is shaken intensively for 24 hours at a temperature of 20 C. The nondissolved substance is filtered off with a porcelain filter crucible having an average pore-size of 6 microns. 5 ml. of the filtrate is mixed with 20 ml. of solution B and 2 ml. of solution C., and kept in the dark for 20 hours at a temperature of 20 C. Then the volume of the reaction mixture is brought up to 50 ml. with solution D and the optical density (O.D.2) at the A max is determined.

The quotient By way of example, the figures which were found in the above tests with a number of azo-coupling components which permit the manufacture of heat-developable diaz'o-type material having good keeping quality are mentioned in the following table. For the sake of comparison the figure for acetoacetanilide is given.

Compound Solubility Melting point lXlO" mol/l. in C.

Acetoacetanilidc 60,500 N-scetoacet-4-benzoylaniline I08 203-204 N,N'-bis(acetoacet)4,4-

diaminodiplienyl-methane 320 l 75 N-acetoacet-4-acetoacet-2-methylaniline 36.5 202-205 N-acetoacet-Z,4,6-tribromoaniline 230 15 8- l 62 N-acetoacet-Z,4,6-trichloroaniline 786 I45- I 4 7 N-acetoacet-4-benzoylamino-5-methyl- Zmethoxyaniline I35 I 78-! 80 N-acetoacet-4-benzoylamino-2,5-

diethoxy-aniline 28 I70- l 74 N-acetoacet-4-benzolamino-2,5-di-nbutoxyaniline l5 l30-l 32 N-acetoacet-4-benzoylamino-S-methoxy- Z-chloroaniline 78 174-170 N-acetoacett-benzoylamino-S-methoxy- 2N-methyl-N-ethoxycarbony laminoaniline 200 lbl-lott N-scetoucet-5-benzoylnminc-2.4-

dimcthyl-aniline 247 llW-IQO N-acetoacet-4( 4'-methoxyphcnyl )-2,5-

dielhoxyaniline l4 Isl-I44 N-acetoacet-4( 4'-methylphenylthio 2.5-diethoxyaniline l -137 N-benzoylacet-4-benzoylnmino-2,5-

dimethoxy-anilinc l.7 lo2-lb7 N-benzoylacet-4-benzoylamino-2.5-

diethocy-aniline l I 79- l 80 2-acetoacetamino-6- ethoxybenzothiazole 108 I5 2-l 5 5 N-acetoacet-octadecylamine l 97-99 N-acetoncet-hexadecylamine 94-97 N,N'-his(acetoacet)decane-l,lO

diamine I25 l50-l52 N,N '-bis(acetoacet)dodecane-l l 2- diamine 238 HJ-ldo The suitability of an acetoacetamide for application as a yellow-coupling azo-component in the diazo-type material according to the invention can be determined with the aid of the above criteria. However, if the compound carries a basic amino group, it is quite possible that the solubility in pure water may differ considerably from the solubility in acid aqueous medium, the medium'which prevails in the light-sensitive layer. For this reason a compound carrying such a group and being soluble to some extent in pure water (e.g. more than 1X10 moi/liter) can yet appear to be unsuitable for practical application although in view of the figures measured it is bound to be satisfactory. Moreover, the acetoacetamides which can be applied in the diazo-type material according to the invention must, as a rule, be free from groups which highly promote the solubility in water, such as sulfonic acid groups and sulfonyl radicals.

Diazo-type material according to the invention which contains an acylacetamide dissolving less than 0.25X20 10" mol/liter in water of 20 C. always shows acceptable keeping quality, if the coupling activity of the acylacetamide, measured in vitro at 20 C. according to the usual method, is.not more than 20 times greater than the coupling activity of acetoacetanilide. Diazo-type materials having excellent keeping quality can also be obtained using acylacetamides with higher coupling activity, provided their water-solubility is less than lXlO mol/liter.

The acylacetamides are applied in the diazo-type material according to the invention in the form of dispersed particles having an average size between 0.1 and 10 microns. To this end the azo-coupling component is dispersed, preferably in an aqueous liquid. With a view to stabilization of the dispersion a hydrophilic organic binder, such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, hydrolysed starch, or high molecular epoxyethane polymers is added. Of course, mixtures of such binders can also be used.

The treatment of the diazo-type material with the dispersion of the acylacetamide can be effected before or after sensitization. However, it is preferred to form the light-sensitive layer in a single treatment with the aid of a liquid which contains all the required ingredients.

Among the acylacetamides which can be applied in the diazo-type material according to the invention with good results, the following compounds stand out as being particularly suitable: N-acetoacet-Z,4,6-tribromoaniline, N- acetoacet-4-acetoacet-2-methylaniline, N-benzoylacet-4- benzoylamino-2,S-dimethoxyaniline, N-acetoacet-4- benzoylamino-2,S-diethoxyaniline, N-benzoylacet-42,5-

diethoxyaniline, 4-acetoacetamino-4-methoxy-2,5-diethoxydiphenyl, N-acetoacet-N-benzoylaminoaniline, N,N'-bis (acetoacet)decanel l O-diamine, N ,N

bis( acetoacet)dodecanel l Z-diamine.

The most attractive compounds are the N,N-bis(acetoacet) derivatives of alkylene diamines with an alkylene group having at least eight carbon atoms. They are fairly accessible, show good dispersibility in water, and the materials made with them have very good keeping quality.

As already stated above, in the diazo-type material according to the invention further azo-coupling components can be employed in addition to the acylacetamide. These components may be water-soluble or water-insoluble, and may or may not be present in the form of dispersed particles. To obtain a black-developing material a blue-coupling azo-component is used besides the acylacetamide. This blue-coupler is preferably 2,3-dihydroxy-naphthalene-6sulfonic acid or a salt thereof. However, fairly black-developing diazo-type materials according to the invention may also be prepared using other blue-couplers, such as the B-ethanolamide of 2-hydroxynaphthalene-3-carboxylic acid. Especially the combination of N ,N-bis(acetoacet)alkylene diamines referred to above with 2,3-dihydroxynaphthalene-6-sulfonic acid may lead to a very fine black-developing material.

For the sensitization of the diazo-type material according to the invention the diazo compounds which are useful in the conventional two-component diazo-type process can be taken. Very suitable diazo compounds are e.g.: 4-diazo-N,N- dimethyl-aniline, 4-diazo-N,N-diethylaniline, 4-diazo-N-ehtyl- N-2-hydroxyaethylaniline, 4-diazo-3-ethoxy-N,N- diethylaniline, 4-diazo-N-methyl-N-cyclohexylaniline, 4- diazo-N-ethyl-N-benzylaniline, 4-diazo-5-chloro-2ethoxy-N- methyl-N-benzylaniline, 4-diazo-2,S-diethoxy-N-ethyl-N- benzylaniline, 4-diazo-2,5-diethoxy-N.N-bis(2'-acetoxyehtyl)-aniline, N-4-diazophenyl-morpholine, N-(4-diazo-2,5- diethoxyphenyl)-morpholine, N-(4-diazo-2,5-di-n-bytoxyphenyl)morpholine, N-(4-diazo-2,S-dimethoxyphenyl) piperidine, N-(4-diazo-2,5-dipropoxyphenyl)-N-methylpiperazine, N-(4-diazo-2,5-diethoxyphenyl)-N'-acetylpiperazine, 4-diazo-2-methoxy-N-methylaniline.

For the stabilization of the light-sensitive layer, acids and acid-reacting salts, such as tartaric acid, citric acid, boric acid, maleic acid, gluconic acid, oxalic acid, phosphoric acid, benzene sulfonic acid, potassium hydrogen sulfate, malic acid, aluminum sulfate, and zinc chloride can be used in the diazotype material according to the invention.

Moreover, a stabilizer of the naphthalene sulfonic acid type can advantageously be added to the light-sensitive layer, e.g, naphthalene-l-sulfonic acid, naphthalene-2-sulfonic acid, naphthalene-l,S-disulfonic acid, naphthalene-2,6-disulfonic acid, naphthalene-2,7-disulfonic acid, naphthalene-1,3,6- trisulfonic acid, l-hydroxynaphthalene-Z-sulfonic acid, 1- hydroxynaphthalene 3-sulfonic acid, l-hydroxynaphthalene- 4-sulfonic acid, l-hydroxynaphthalene-5-sulfonic acid, 1- hydroxynaphthalene-8-sulfonic acid, Z-hydorxynaphthalenel-sulfonic acid, 2-hydroxynaphthalene-fi-sulfonic acid, 2-

hydroxynapthalene-7-sulfonic acid, 2-hydroxynaphthalene-8- sulfonic acid, l-hydroxynaphthalene-3,6-disulfonic acid, 1- hydroxynaphthalene-3 ,8 disulfonic acid, l-hydroxynaphthalene-4,8-disulfonic acid, 2-hydroxynaphthalene-3,6- disulfonic acid, 2-hydroxynaphthalene-3,7-disulfonic acid, 2- hydroxynaphthalene6,8-disulfonic acid, I, hydroxynaphthalene,3,6,8-trisulfonic acid, or 2-hydroxynaphthalene.3,6,8-trisulfonic acid. Preferably, these stabilizers are used as watersoluble salts, e.g. as sodium salts.

The substance which upon heating creates the medium in which coupling of the diazo compound and the azo-coupling component can occur, is preferably a developing agent according to the Belgian Pat. Application No. 29,782. However, good materials can also be prepared using other water-insoluble developing agents.

The support of the diazo-type material according to the invention may be paper, tracing paper, tracing linen, opaque linen, synthetic paper, metal foils, glass fabric, polyester film, and the like.

it will be clear that the diazo-type material according to the invention may also contain mixtures of water-insoluble acylacetamides and that, besides the acylacetamide, very different diazo compounds, azo-coupling components, acidreacting compounds, developing agents, binders, and further auxiliary agents can be used.

In the following examples developing agents as described in the Dutch Pat. application 6,402,452 and the Belgian Pat. application 29,782 are used.

As binders polyvinyl alcohol, polyvinyl pyrrolidone, and hydrolysed potato starch are chiefly used in the examples. These binders are always added to the coating liquids in the form of an aqueous solution. Unless otherwise mentioned, it is to be understood that:

P.V.A.-solution is an aqueous solution which contains g./l. of a low-viscous polyvinyl alcohol having a degree of hydrolysis of 98.5 percent;

P.V.P.-solution is an aqueous solution which contains 200 g./l. ofa polyvinyl pyrrolidone with K-value 30 (mol. weight about 40,000);

starch solution is an aqueous solution which contains 100 g./l. of hydrolysed potato starch.

To achieve good spreading of the various liquids on the support surface, the addition of a wetting agent is often required. A great many wetting agents can be used. Unless otherwise stated, in the examples by wetting agent is always to be understood a solution which contains I00 ml./l. of a condensate of one mole of an aromatic amine with l0 moles of epoxyethane.

Dispersions can be prepared in many ways. The dispersions according to the examples have always been prepared by grinding the given mixture of substances in a ball-mill for 24 hours. Thus finely divided particles having an average size of l-7 microns are obtained, dependent, inter alia, on the substance to be ground and the auxiliary agents which are present in the grinding liquid.

In the examples, unless emphatically stated otherwise, an azo-coupling component dispersion means an aqueous dispersion which contains per litre 100 g. of the insoluble yellow-coupling azo-components mentioned in the example 20 g. of polyvinyl alcohol (low-viscous, degree of hydrolysis 98.5 percent) and 40 g. of polyvinyl pyrrolidone K-value 30).

EXAMPLE I A dispersion is prepared from a mixture containing:

g. of melamine sebacate 5 g. of citric acid 50 g. of the sodium salt of 2,3-dihydroxynaphthalene-6-sulfonic acid 30 g. of thiourea 30 g. of silica with an average particle size between 2 and 4 microns g. of resorcinol 200 ml. of starch solution 250 ml. of P.V.P.-solution and 300 ml. ofwater.

To the dispersion are added:

ml. of wetting agent 9 g. of 4-morpholino-2,S-diethoxybenzene diazonium hydrogen sulfate, upon which the volume is brought up to 1 litre with water and the dispersion is made homogeneous.

From the dispersion 2 portions of 480 ml. each are taken.

A. To the first portion is added 20 ml. of a dispersion prepared from mixture of 200 g. of N- acetoacet-Z,4,6-tribromoaniline and 1,000 ml. of water and the liquid thus obtained is made homogeneous.

B. To the second portion is added 20 ml. of a dispersion prepared from a mixture of 100 g. of

acetoacetanilide and 1,000 ml. of water (in this dispersion a part of the acetoacetanilide is in a dissolved state) and the liquid thus obtained in made homogeneous.

With each of the liquids A and B a sheet of white base paper of 80 g/m for the diazo-type process is sensitized. The applied quantity of diazo compound amounts to 0.45 millimole per m After the sensitization the sheets are dried to a moisture content of4 percent.

A strip of both sheets is kept for 24 hours in a light-tight room with a temperature of 35 C. and a relative humidity of 75 percent. Then the strips are exposed until all the diazo compound has bleached out. On strip A a light violet fog is observed as a result of a small premature azo-dyestuff formation. On strip B a conspicuous yellow-brown fog is present because of a rather strong premature coupling between the yellowcoupling azo-component and the diazo compound. Light-sensitive paper B thus has considerably lower keeping quality than light-sensitive paper A.

A second strip of the sheets A and B is imagewise exposed underneath a transparent original until underneath the transparent portions of the original all the diazo compound has bleached out. The copy is developed by bringing its face in contact for ID seconds with a metal surface with a temperature of l50 C. The copies show a brown-black image on a clear white background.

EXAMPLE II A dispersion is prepared from a mixture containing:

175 g. of 2,4-diamino-6-n-propylamino-l ,3,5-triazine sebacate 5 g. of tartaric acid 50 g. of the sodium salt of 2,3-dihydroxynaphthalene-6-sulfonic acid g. of B-ethanolamide of Z-hydroxynaphthalene-3-carboxylic acid.

30 g. of silica (2-4 microns) 200 ml. of starch solution 250 ml. of P.V.P.-solution and 300 ml. of water 400 ml. of this dispersion is diluted with water to make 700 After the dispersion has been made homogeneous again,

5 ml. of wetting agent 25 ml. of an azo-coupling component dispersion on the basis of N acetoacet-4-benzoylaminc-2,5-diethoxyaniline and 3.2 g. of 4-morpholino-2,5 -diethoxybenzene diazonium hydrogen sulfate are added.

With the light-sensitive dispersion thus prepared, white base-paper of 80 glm for the diazo-type process is sensitized. Per m O,4 millimole of diazo compound is used. After the sensitization the paper is dried to a moisture content of 4 percent. A sheet of the diazo-type paper thus obtained is imagewise exposed underneath an ink drawing on tracing paper until underneath the transparent portions of the drawing all the diazo compound has bleached out, and is then developed as described in example I. The copy shows a black image on a white background.

If, instead of the insoluble yellow-coupling azo-component mentioned, an equivalent quantity of acetoacetanilide had been used in the above light-sensitive dispersion, a diazo-type paper having much lower keeping quality would have been obtained.

EXAMPLE III A dispersion is prepared from a mixture 150 g. of melamine sebacate 5 g. of oxalic acid 200 ml. of P.V.A.-solution 240 ml. of P.V.P.-solution and 375 ml. ofwater To 500 ml. of this dispersion 200 ml. of water is added,

and after homogenization 25 g. of the sodium salt of naphthalene-l ,3,6-trisulfonic acid 5 ml. of wetting agent and 3.5 g. of N-acetyl-N-(4-diazo-2,5diethoxyphenyl) piperazine are dissolved in the dispersion.

Subsequently, to the liquid thus prepared 50 ml. of an azo-coupling component dispersion on the basis of N-acetoacet-4-(4'methoxy) phenyl-2,5-diethoxyaniline is added.

The dispersion thus obtained is made homogeneous. and thin translucent base paper of 60 g/m for the diazo-type process is sensitized with the dispersion. After the sensitization the paper is dried. A sheet of the diazo-type paper thus prepared is imagewise exposed underneath a pencil drawing on tracing paper until underneath the transparent portions of the drawing the diazo compound has largely bleached out. The copy is developed by guiding it with the back over a surface with a temperature of l50 C., the contacting time being 10 seconds. The copy shows an intensive yellow image on a foggy yellow background. It is eminently suitable as an intermediate original for making further copies on diazo-type material. I

If, instead of the insoluble yellow-coupling azo-compound mentioned, an equivalent quantity of acetoacetanilide had been used in the light-sensitive dispersion described above, a diazo-type paper of much lower keeping quality would have been obtained.

EXAMPLE IV A dispersion is prepared from a mixture containing:

200 g. of melamine adipate 5 g. of citric acid 50 g. of the sodium salt of 2,7-dihydroxynaphthalene-3,6-

naphthalene disulfonic acid 30 g. of thiourea 30 g. of stearoyl amide 200 ml. of starch solution 250 ml. of P.V.P.-solution 250 ml. ofwater 500 ml. of the dispersion is diluted with water to make 700 After the dispersion has been made homogeneous again.

5 ml. of wetting agent 50 ml. of an azo-coupling component dispersion on the basis of N-benzoylacet-4-benzolylamino-2,5-diethoxyaniline and 4 g. of morpholino-Z,S-diethoxybenzene hydrogen sulfate are added.

The light-sensitive dispersion thus prepared is made homogeneous, after which white base paper of g/m for the diazo-type process is sensitized with the dispersion. After the sensitization the paper is dried. A sheet of the diazo-type diazonium paper thus prepared is imagewise exposed and developed as described in Example Ill. The copy shows a yellow-brown image on a foggy background.

If instead of the yellow-coupling azo-component used, an equivalent quantity of the sodium salt of 4-acetoacetaminonaphthalene-l-sulfonic acid, which azo-coupling component is reasonably water-soluble, had been used in the light-sensitive dispersion, a diazo-type paper of much lower keeping quality would have been obtained.

EXAMPLE \I basis of N-acetoacet-4-acetoacet-2-methylaniline are added.

The light-sensitive dispersion thus prepared is made homogeneous, after which white base paper of 80 g/m2 for the diazo-type process, which has been pretreated with noncolloidal silica, is sensitized with the dispersion. After sensitization the paper is dried. A sheet of the diazo-type paper thus obtained is imagewise exposed underneath an ink drawing on tracing paper until underneath the transparent portions of the drawing all the diazo compound has bleached out, and is then developed as described in example Ill. The copy shows a black image on a clear white background.

EXAMPLE VI A dispersion is prepared from a mixture containing:

150 g. of melamine sebacate g. of tartaric acid 50 g. of the sodium salt of 2-hydroxynaphthalene-hthalenc- 3,6disulfonic acid 30 g. of silica (2-4 microns) 500 ml. of P.F.A.-solution 200 ml. of a solution of 50 g. of polyvinyl pyrrolidone K-90 in 1,000 ml. of water 150 ml. ofwater 500 ml. of the dispersion thus obtained is diluted with water to make 700 ml. and then ml. of wetting agent 5 g. of diethylaminobenzene diazonium chloride/zinc chloride double salt 5 g. of the sodium salt of 8-hydroxynaphthalene-1,3,6-trisulfonic acid and 50 ml. of an azo-coupling component dispersion on the basis of N-acetoacet-4-l4'-methylphenylthio)-2,5- diethoxyaniline are added.

The light-sensitive dispersion thus prepared is made homogeneous, after which white base paper of 80 g/m for the diazo-type process is sensitized with the dispersion. A sheet of I the diazo-type paper thus obtained is imagewise exposed underneath an ink drawing on tracing'paper until underneath the transparent portions of the drawing all the diazo compound has bleached out, and is then developed as described in Example Ill. The copy shows an orange-yellow image on a foggy background.

EXAMPLE vn A dispersion is prepared from a mixture containing: triazinesebacate Egg. of 2,4- dia mino-6-methyl-l ,3,5,-triazinesebacate 5 g. of citric acid v I 50 g. of the sodium salt of 2,3-dihydroxynaphthalene-6-sul- I fonic acid 12 sFi Efthioiirea 30 g. ofsilica (2-4 microns) 200 ml. ofstarch solution 250 ml. of RV .P.-solution and 250 ml. ofwater 500 ml. of this dispersion is diluted with water to make 750 After the diluted dispersion has been made homogeneous again, on white base paper of g/m for the diazo-type process a thin layer containing about 5 g. of developing agent per m is formed. After drying, the paper side thus treated is sensitized with a solution containing 8 g. of 4-morpholino-2,S-diethoxybenzene diazonium chloride/zinc chloride double salt 1 g. of citric acid 250 ml. of starch solution 250 ml. ofP.V.A.-solution ml. of an azo-coupling dispersion on the basis of N- acetoacetoctadecylamine and 380 ml. of water and dried.

A sheet of the diazo-type paper thus obtained is imagewise exposed underneath an ink drawing on tracing paper until underneath the transparent portions of the drawing all the diazo compound has bleached out, and is then developed as described in example Ill. The copy shows a blue-black image on a white background.

EXAMPLE VI" A dispersion is prepared from a mixture containing g. of melamine sebacate 5 g. of citric acid 50 g. of the sodium salt of 2,3-dihydroxynaphthalene-6-sulfonic acid 200 ml. of P.V.A.-solution 250 ml. of P.V.P.-solution 1 ml. of wetting agent 10 g. of 4-diethylaminobenzene diazonium chloride/zinc chloride souble salt and 300 ml. of water To the dispersion, thus prepared, 200 ml. of an aqueous dispersion containing 100 g./l. of N-acetoacet-4- benzolylamino-Z,S-di-n-butoxyaniline and 20 g./l. of gum arabic is added, after which the liquid thus obtained is made homogeneous. V

Sized natural tracing paper of 80 g/m for the diazo-type process is sensitized with the sensitizing liquid thus prepared. After sensitization the paper is dried. A sheet of the diazotype paper thus obtained is imagewise exposed underneath an ink drawing on tracing paper until underneath the transparent portions of the drawing all the diazo compound has bleached out, and is then developed as described in example Ill. The copy shows a yellow-brown image on a white background and is eminently suitable asan intermediate original for making further copies on diazo-type material.

EXAMPLE lX A dispersion is prepared from a mixture containing: 200 g. of di(octadecylammonium )oxalate 15 g. of oxalic acid 400 ml. ofP.V.A.-solution 400 ml.;of water With this dispersion white base paper of 80 g/m for the diazo-type process is coated with a layer containing about 6 g. of developing agent per m2. After drying, the treated side of the paper is sensitized with a liquid containing 10 g. of 4-N,N-bis(2'-acetoxyethyl)amino-2,S-diethoxybenzene diazonium chloride/zinc chloride double salt 30 g. of the sodium salt of 2,3-dihydroxynaphthalene-6-sulfonic acid 10 g. of oxalic acid 50 g. of rice starch 10 ml. of wetting agent 250 ml. of P.V.A.-solution 250 ml. of starch solution 40 ml. of a azo-coupling component dispersion on the basis of N-acetoacet-4-benzolyamino-5-methoxy-2-N-methyl- N-ethoxycarbonylaminoaniline and 360 ml. of water and dried.

A sheet of the diazo-type paper thus obtained is iamgewise exposed underneath an ink drawing on tracing paper until underneath the transparent portions of the drawing all the diazo compound has bleached out, and is then developed as described in example Ill. The copy shows a dark violet-brown image on a white background.

EXAMPLE X On tracing paper which has been pretreated with a developing agent dispersion as described in example IX, and thereafter dried, a light-sensitive layer is formed by applying a liquid containing:

15 g. of 4-morpholino-2,S-diethoxybenzene diazonium hydrogen sulfate 20 g. of the sodium salt of 2,3dihydroxynaphthalene-6-sulfonic acid l g. of oxalic acid 40 g. of the sodium salt of 7-hydroxynaphthalene-l ,3-disulfonic acid 50 g. of rice starch 250 ml. of P.V.A.-solution 250 ml. of starch solution l 10 ml. of an azo-coupling component dispersion on the basis of N-acetoacet-4-benzoylaminoaniline 300 ml. ofwater and drying.

A sheet of the diazo-type paper thus obtained is imagewise exposed underneath an ink drawing on tracing paper until underneath the transparent portions of the drawing all the diazo compound has bleached out, and is then developed as described in example Ill. The copy shows a dark brown image on a clear background.

EXAMPLE Xl White base paper of 80 g/m for the diazo-type process, which has been pretreated with a developing agent dispersion as described in example IX and then dried, is sensitized with a liquid containing:

1 l g. of 4-N,N-bis(2'-acetoxyethyl)amino-2,5-diethoxybenzene diazonium chloride/zinc chloride double salt 10 g. of oxalic acid 30 g. of the sodium salt of 2,3-dihydroxynaphthalene-6-sulfonic acid g. of rice starch 10 ml. of wetting agent 250 ml. ofP.V.A.-solution 250 ml. of starch solution 400 ml. of water 80 ml. of an azo-coupling component dispersion on the basis of N-acetoacethexadecylamine and dried.

A sheet of the diazo-type paper thus obtained is imagewise exposed underneath an ink drawing on tracing paper until underneath the transparent portions of the drawing all the diazo compound has bleached out, and is then developed as described in example [I]. The copy shows a green image on a white background.

EXAMPLE Xll To a developing agent dispersion prepared as described in example IX 10 ml. of wetting agent and 40 ml. of an azo-coupling component dispersion on the basis of N-benzoylacet-4-benzoylamino-2,5-dimethoxyaniline are added. After homogenization of the dispersion, white base paper of 80/g/m for the diazo-type process is treated therewith. After drying, the treated side is sensitized with a sensitizing liquid as described in example XI, from which the azo-coupling component dispersion has been omitted.

A sheet of the diazo-type paper thus obtained is imagewise exposed underneath an ink drawing on tracing paper until underneath the transparent portions of the drawing all the diazo compound has bleached out, land is then developed as described in example Ill. The copy shows a violet-brown image on a white background.

While numerous details, examples and explanations have been set forth hereinabove to illustrate the practice and principles of the invention, it will be understood that the invention herein described can be applied in various other ways and by the use of various compounds and materials other than those particularly named. it is not intended to be restricted to particulars of the foregoing description except as may be required for fair construction of the appended claims.

What is claimed is:

1. In a heat-developable diazo-type material comprising a sheet shaped support having coated thereon so as be accessible one to another during heating a light sensitive diazo compound, an azo-coupling component, an acid-reacting compound, and a finely-divided developing agent that is substantially water-insoluble, the improvement wherein said developing agent comprises a reaction product of an organic amine and an organic dicarboxylic acid, which has a solubility of less than 2 g./liter in water at 20 C. and is present in the form of dispersed particles having an average size of 0.1 to 10 microns, and the azo-coupling component comprises an acylacetamide which has the general formula R,CH,CO R R being an acyl group and R being an amido residue derived from a primary amine having a molecular weight of at least 150, and which melts above 50 C., has a solubility of less than l l0 mol/liter in water at 20 C., and is present in the form of dispersed particles having an average size between 0.l and 10 microns.

2. Heat-developable diazo-type material according to claim 1, wherein the acylacetamide is one having a solubility of less than 0.25 XlO mol/liter in water at 20 C.

3. Heat-developable diazo-type material according to claim 2, said acylacetamide having a coupling activity which, measured in vitro, is not more than 20 times greater than the coupling activity of acetoacetanilide.

4. Heat-developable diazo-type material according to claim 1, wherein the acylacetamide is an amide of acetoacetic acid.

5. Heat-developable diazotype a material according to claim 1, wherein said amido residue is one derived from 2,4,6- tribromoaniline.

6. Heat-developable diazo-type material according to claim 1, wherein said amido residue is one derived from 4- benzoylamino-2,S-dialkoxyaniline.

7. Heat-developable diazo-type material according to claim 1, wherein the acylacetamide is a N,N-bis(acylacet)-alkylenediamine having an alkylene group containing at least 8 C-atoms.

8. Heat-developable diazo-type material according to claim 1, wherein the azo-coupling component comprises, besides the acylacetamide, a quantity of a compound capable of forming a blue dyestuff by coupling with said diazo compound so that said layer when developed will give a substantially black image.

9. Heat-developable diazo-type material according to claim 8, said blue coupling compound being 2,3-dihydroxynaphthalene-6 sulfonic acid or a salt thereof.

10. Heat-developable diazo-type material according to claim 1, said developing agent being a salt of melamine and an alkane dicarboxylic acid having 9-12 C atoms.

11. In a heat-developable diazo-type material comprising a support carrying a light-sensitive layer which contains a lightsensitive diazo compound, an azo-coupling component capable of coupling with said diazo compound to form dyestuff giving a substantially black color, an acid-reacting compound as a stabilizer, a water-soluble hydrophilic organic binder. and as a developing agent dispersed particles of a compound which kylenediamine having an alkylene group containing at least 8 C-atoms and having a solubility of less than 0.25 l0 mol/liter in water at 20 C., said developing agent and said yellow-coupling compound each being present in said layer in the form of dispersed particles of between 0.l and 10 microns in average size.

it I I! t i UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,615,537 Dated October 26, 1971 Leonardus Jacobus Antonius Giesen and Hubertus Wilhelmus Hen'ricus Maria Roncken Assignors to Van Der Grinten N.V. of

Venlo, Netherlands It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

In place of "10 read "10' at each occurrence thereof, to wit:

Abstract, line 11.

Column 3, ling 32.

Column 4, lines 2 and 74. Column 5 lines 41, 43 and 45. Column i l, lines 3M and 39, and Column 16, line 2.

I Column 1: Line 56, in plac of "10 read "10' and in place of "10 read "10' Line 73, in place of "resis" read "resin".

Column 4: Line 17, in place of "shown" read "show" Line 37, in place of "maige" read 'am ne" Line 72, in place of "10 read "10 column 5; Lines 3 and 5, in place of "10 read "10- Line 8. in place of 10 read "10: e

Column 6; Line 32, transpose "135-137" to the right-hand data column headed "Melting point in c."

Lines 54 and 70, in place oi "10 read "10' Line 62, in place of "20 1o read "10' Column 7: Line 47, in place of "ehtyl" read "ethyl" Lines 52-53, in place of "acetoxyehtyl" read "acetoxyethyl"; L

Line 7 in place of "hydorxynaphthalene" read "hydroxynaphthalene".

Column 10: Line 12, after "mixture" read "containing".

Line 16, in place of "240" read "250". Line 60, after "solution" delete Column 11: Line 59, in place of "-14' read "-4'" Line 72, delete "triazinesebacate".

Column 14: Line 6, in place of "land" read "and".

Signed and sealed this 30th day of May 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Commissioner of Patents Attesting Officer 

2. Heat-developable diazo-type material according to claim 1, wherein the acylacetamide is one having a solubility of less than 0.25 X 10 3 mol/liter in water at 20* C.
 3. Heat-developable diazo-type material according to claim 2, said acylacetamide having a coupling activity which, measured in vitro, is not more than 20 times greater than the coupling activity of acetoacetanilide.
 4. Heat-developable diazo-type material According to claim 1, wherein the acylacetamide is an amide of acetoacetic acid.
 5. Heat-developable diazo-type a material according to claim 1, wherein said amido residue is one derived from 2,4,6-tribromoaniline.
 6. Heat-developable diazo-type material according to claim 1, wherein said amido residue is one derived from 4-benzoylamino-2, 5-dialkoxyaniline.
 7. Heat-developable diazo-type material according to claim 1, wherein the acylacetamide is a N,N''-bis(acylacet)-alkylenediamine having an alkylene group containing at least 8 C-atoms.
 8. Heat-developable diazo-type material according to claim 1, wherein the azo-coupling component comprises, besides the acylacetamide, a quantity of a compound capable of forming a blue dyestuff by coupling with said diazo compound so that said layer when developed will give a substantially black image.
 9. Heat-developable diazo-type material according to claim 8, said blue coupling compound being 2,3-dihydroxynaphthalene-6 sulfonic acid or a salt thereof.
 10. Heat-developable diazo-type material according to claim 1, said developing agent being a salt of melamine and an alkane dicarboxylic acid having 9-12 C atoms.
 11. In a heat-developable diazo-type material comprising a support carrying a light-sensitive layer which contains a light-sensitive diazo compound, an azo-coupling component capable of coupling with said diazo compound to form dyestuff giving a substantially black color, an acid-reacting compound as a stabilizer, a water-soluble hydrophilic organic binder, and as a developing agent dispersed particles of a compound which has a solubility of less than 2 g./liter in water at 20* C. and upon being heated above 100* C. creates a medium in which coupling of said diazo compound and said azo-coupling component will take place, the improvement wherein said azo-coupling component comprises as a blue-coupling compound 2,3-dihydroxynaphthalene-6-sulfonic acid or a salt thereof and as a yellow-coupling compound a N,N''-bis(acylacet)-alkylenediamine having an alkylene group containing at least 8 C-atoms and having a solubility of less than 0.25 X 10 3 mol/liter in water at 20* C., said developing agent and said yellow-coupling compound each being present in said layer in the form of dispersed particles of between 0.1 and 10 microns in average size. 